Abstract: A method of fabricating a semiconductor device. A series of layers is deposited on a semiconductor substrate of a first conductivity type to form a shielding arrangement, including an upper part and a lower part, to provide a shield against accelerated ions. This is followed by forming openings in the shielding arrangement by microlithographic processes and anisotropic etching, and then implanting ions via the openings to form one of a base area and a base-connection area of the first conductivity type. Edges of the openings are displaced by isotropic etching of the lower part of the shielding arrangement.